Wallet app with NFC

[[Overview]](url)
A production-grade Fintech mobile application and backend ecosystem. Designed for the 2026 digital economy, this project provides a complete foundation
for a Unified Fiat/Crypto wallet with hardware-level security and NFC capabilities.

Technical Stack
* Mobile: React Native / Expo (Development Build).
* Backend: NestJS (Node.js) with TypeScript.
* Database: PostgreSQL (Postgres 15) with Prisma ORM.
* Native Modules: Custom Kotlin (Android) Bridge for Google Pay / Tap-and-Pay.
* Security: AES-256-CBC Encryption for Private Keys, Bcrypt Password Hashing.
* Containerization: Full Docker Compose setup for local development.

Key Features (Fully Implemented)
1. Unified Financial Ledger: ACID-compliant PostgreSQL schema handling Fiat (USD) and Crypto (ETH/ERC20) balances with high-precision decimal math.
2. Native Biometric Security: Integrated FaceID/Fingerprint lock screen using the phone's Secure Enclave.
3. Hatch "Tap-to-Pay": Custom Android Native Module to trigger the Google Play Services Tap-and-Pay API.
4. Standalone Demo Mode: The app includes a persistent local vault (SecureStore) allowing for 100% offline demos with Top-up, Withdraw, and NFC
simulations.
5. Atomic Registration: Automated transaction flow that creates User, Fiat Wallet, and Real Cryptographic Ethereum Wallet in a single database operation.
6. Premium UI/UX: Google Pay style card carousel with smooth swiping, dark mode, and real-time transaction history.

What’s Included
* Full Source Code: 100% clean, commented, and modular code for both App and Backend.
* Standalone APK: Production-ready binary for immediate testing.
* Technical Documentation: Complete architectural overview and deployment guide.
* Postman Collection: Ready-to-use API documentation for all endpoints (Auth, Payment, Wallet).

Ideal For
* Startup founders looking for a ready-made Fintech MVP.
* Agencies needing a white-label wallet solution for clients.
* Developers wanting a robust reference for Native NFC and Biometric implementations in React Native.